Hi there.
From memory, there's a setting in the SME 7 server-manager panel that allows you to delegate the mail serving to another box on your local network, you'd just point that at the IP of your mail-server box. I think it's "edit email settings", but I'm not 100% sure.
URL is
http://yourservername/server-managerIt will only work on your local network; UN = admin, PW = whatever you set the root password to.
As for FTP (and presumably you want to use that box as a web-server as well), I'm pretty sure SME 7 has port forwarding built in to the server-manager - you'd just use that to forward ports 80, 443 and 21 to the web-server box IP.
Another thought, if you wanted to host the home directories on another server, I'd:
[1] Rsync the /home directory to the new server
[2] Delete the old server home directories, then mount new server /home directory on the old (SME) server at the same place (/home)
[3] Alter startup files to make the change permanant.
Server-manager would automatically take care of the template files - you wouldn't need to worry about things being overwritten on updates. If you want to make a more specific change to a config file, you just need to create a custom template:
eg if you wanted to edit /etc/dir/something.config
you usually just do something like this:
mkdir -p /etc/e-smith/templates-custom/etc/dir/something.config
pico /etc/e-smith/templates-custom/etc/dir/something.config/line001
(insert your configuration lines)
expand-template /etc/dir/something.config
Then:
less /etc/dir/something.config
(to check that it actually worked)
Only problem with the setup you described is that you would need to set up 3 sets of user accounts - one for mail, one for domain logons and one for web/ftp access. There might be some way to copy them across with an LDAP tool.
Hope that helps.
Silas.